The present invention relates to a burner device and to a method for heating a furnace space. In particular, the invention relates to burner devices arranged in the ceiling and/or side walls of a heating furnace, and to a heating furnace comprising such burners.
In many industrial combustion applications, it is preferable to use an oxidant with high oxygen contents, so-called oxyfuel combustion. This yields improved heating efficiency and may decrease NOx formation so long as peak flame temperatures can be controlled.
One general problem of using such high-oxygen oxidant is to achieve adequate peak flame temperature control.
A specific problem in the case of burners arranged in the ceiling or side walls of heating furnaces is that the direct heating power reaching the material in the furnace must be limited in order to avoid overheating of the material.
Previously, it has been proposed to impart a rotational motion of supplied fuel or oxidant, so that centrifugal forces provide for a divergence after exit from the burner. This provides for a plate-shaped flame, which can be arranged to propagate along the ceiling or side wall and as a result be sufficiently removed from the heated material. In another previously known solution, the fuel or oxidant is supplied at an angle from the longitudinal axis of the burner, to provide a similar effect.
It has proved difficult to construct a burner robustly yielding such a controlled, plate-shaped flame due to material degradation caused by the high temperature and aggressive environment inside an industrial furnace. In particular, it is problematic to use high-oxygen oxidants with prior art plate-shaped flame burners while at the same time controlling peak flame temperatures and avoiding material overheating as explained above.